1. Field of the Invention
The present invention relates to a liquid crystal display module.
2. Discussion of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, many efforts and studies are being made to develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these flat panel displays, LCD devices have many advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements.
In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmissivity of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a perspective view of a LCD module according to the related art.
Referring to FIG. 1, the LCD module 10 includes a liquid crystal panel 45, a backlight assembly 65, a main supporter 60, a top case 70 and a bottom case 15.
The bottom case 15 is located at the bottom of the LCD module 10. A reflector 20 is located on an inner surface of the bottom case 15. The backlight assembly 65 is located on the reflector 20. The backlight assembly 65 includes a plurality of lamps 30 parallel to one another, and a plurality of optical sheets 40 on the lamps 30. The plurality of optical sheets 40 includes a diffusion sheet 41, a prism sheet 42 and a protection sheet 43. The main supporter 30 has a rectangular frame shape and surrounds the plurality of optical sheets 40 and the liquid crystal panel 45. The main supporter 30 is coupled with the bottom case 15. The top case 70 is located at the top of the LCD module 10. The top case 70 covers peripheral portions of the liquid crystal panel 45 and is coupled with the main supporter 60 and the bottom case 15. A pair of lamp guiders 35 fixes both ends of the lamps 30. The lamp guiders 35 are coupled with the bottom case 50.
A gate driving PCB (printed circuit board) 54 and a data driving PCB 56 are coupled with the liquid crystal panel 45 using TCP (tape carrier package) technology. TCP technology uses a TAB (tape automated bonding) film which connects the driving PCBs 54 and 56 to the liquid crystal panel 45. However, it is difficult to make inner leads in the TAB film straight, and there thus is a limit to achieving the fine pitch required for high resolution.
To achieve the fine pitch, COF (chip on flexible printed circuit) technology has been suggested. COF technology uses a COF film on which gate or data driving chip is installed directly. The COF film has a double-layered structure without adhesives and copper lines in the COF film are very thin, for example, 8 μm, and the fine pitch is thus feasible. Accordingly, the COF film is employed in high resolution LCD devices.
However, as the size of the LCD module has recently increased, due to material property and elasticity of the COF film connected to the liquid crystal panel, the liquid crystal panel is thus lifted up off a correct position. Accordingly, the LCD module is defective, and production efficiency is reduced.
FIG. 2A is a perspective view illustrating a portion of the LCD module according to the related art, and FIG. 2B is a perspective view illustrating a portion of the main supporter of the LCD module according to the related art.
Referring to FIGS. 2A and 2B, the liquid crystal panel 45 is placed on an inner peripheral portion of the main supporter 60. A plurality of COF films 80 connect the data driving PCB 56 to the liquid crystal panel 45. The COF film 80 is bent at about 90 degrees angle along an outside of the main supporter 60, and the data driving PCB 56 is thus placed on the outer side of the main supporter 60.
A plurality of moving obstacles 85 are installed on a side frame of the main supporter 60. The moving obstacle 85 functions to prevent the liquid crystal panel 45 from moving away in a horizontal direction and fix the liquid crystal panel 45 at a right position.
The large-sized LCD modules, for example, of 19 inches or more may have a problem that the liquid crystal panel 45 is lifted up due to the elasticity of the COF film 80 after an assembling process while the smaller-sized LCD modules seldom have the problem.
FIG. 3 is a view illustrating the problem that the liquid crystal panel of the LCD module according to the related art is lifted up.
Referring to FIG. 3, the backlight assembly (65 of FIG. 1) is coupled with the main supporter 60, then the liquid crystal panel 45 and the data driving PCB 56 are placed on the main supporter 60, then a gasket 90 is coupled with an outer side of the data driving PCB 56, then the top case (70 of FIG. 1) is assembled, and thus, the LCD module is completed. The gasket 90 functions as a buffer to prevent the data driving PCB 56 from being damaged due to an external impact or pressure in an assembling process. For example, the gasket 90 is made of a styrofoam.
The COF film 80 is bent at about a 90 degree angle by a worker's applying a force to the COF film 80. After the COF film 80 is bent and the gasket 90 is located on the data driving PCB 56, the top case is assembled. When the top case is assembled, the gasket 90 is pressed by a force, for example, the top case, and the data driving PCB 56 is thus closely attached to and fixed to the main supporter 60. Sine the data driving PCB 56 is closely attached to the main supporter 60 due to pressing the gasket 90, the COF film 80 is warped. In other words, the data driving PCB 56 goes toward the main supporter 60 due to pressing the gasket 90, and thus, the data driving PCB 56 changes in position between before assembling the top case and after assembling the top case. This position change of the data driving PCB 56 causes the COF film 80 to be warped. As the LCD module increases in size, and the COF films 80 in the LCD module increase in number. Accordingly, in the large-sized LCD module, the elastic force of the COF films 80 due to the warpage of the COF films 80 is large so that the liquid crystal panel is lifted up by a distance “F”.
As described above, the problem of abnormally moving the liquid crystal due to the elastic force of the COF films occurs in the assembling process, and the production efficiency is thus much reduced.